Brain imaging following stroke
Dr. Andrew Demchuk would agree. As a stroke neurologist at Calgary's Foothills Hospital, he sees the need for better stroke treatment every day. "Stroke is a very challenging disease with few proven treatments," he says. "Just look at the numbers, and you'll see the need for advances. There are approximately 5,000 strokes per year in Alberta and thousands of stroke survivors in the province. The burden of stroke on families is heartbreaking. Given our aging population, the rising economic cost of stroke care creates a compelling argument for further stroke research."
Dr. Demchuk's research centres on imaging brain and blood vessels. He is trying to establish target populations for new stroke treatments by selecting patients based on imaging tests performed in the emergency department. Dr. Demchuk explains: "Stroke neurologists like to say 'different strokes for different folks.' What we mean is that stroke is a very complex disease with multiple causes, varying presentation, varying severity, and it happens at different locations throughout the brain. And stroke is extremely time dependent. We need be able to treat patients quickly. To do that, we must somehow identify groups of patients and learn how to treat them effectively."
One of his studies uses computed tomography (CT) angiography, a type of CT scan that gives detailed images of the blood vessels to determine which patients require additional therapy beyond intravenous tissue plasminogen activator (tPA). This drug is used to dissolve clots in patients who have had an ischemic stroke (the most common type of stroke, which is caused by a blockage of blood flow to the brain). But tPA is not particularly effective at dissolving big clots in large veins. In these cases, it may be better to thread a catheter into the vein and physically remove the clot. A large international clinical trial that is currently underway compares tPA treatment with combined tPA and catheter treatment. The University of Calgary is the imaging analysis centre for this trial, which involves 60 centres in North America, four in Australia, and more to be added in Europe. "We're on our way to becoming an international leader in stroke trials," says Dr. Demchuk.
Another pioneering study headed by Dr. Demchuk used magnetic resonance imaging (MRI) to look at the brain and blood vessels of people who have had a mini-stroke—more technically called a transient ischemic attack (TIA)—and determine who is likely to have a major stroke. Time is critical when dealing with a TIA, which happens when a clot stops blood from flowing to the brain for a short time. About 10% of patients who have had a TIA will have a second, more severe stroke within 90 days. Dr. Demchuk's study showed that MRI can accurately predict who will have another stroke. "That's vital information; however, MRI is not available in the emergency departments of most hospitals in Canada," notes Dr. Demchuk. "We had to look for a more practical tool."
The five signs of stroke
If you experience any of these symptoms, CALL 911 or your local emergency number immediately:- Weakness—sudden loss of strength or sudden numbness in the face, arm, or leg, even if temporary
- Trouble speaking—sudden difficulty speaking or understanding or sudden confusion, even if temporary
- Vision problems—sudden trouble with vision, even if temporary
- Headache—sudden severe and unusual headache
- Dizziness—sudden loss of balance, especially with any of the above signs.
Source: Heart and Stroke Foundation of Canada
www.heartandstroke.ca